Several approaches for making anti-copy articles are known in the art. For example, one approach involves decreasing the contrast between the indicia present on the sheet of paper and the paper background so that the indicia will be practically invisible to a copying machine. Decreasing the contrast can be accomplished by applying a set of color forming dyes to the sheet of paper that closely matches the color of the indicia or by covering the document with a transparent film of selected colors, such as red, orange, or brown. Another approach involves the use of micro-optical elements that redirect the exposure light generated from a copying machine such that the light does not contact the document. This process can be accomplished by using a set of micro-optical elements that focus the exposure light on to light absorbing elements.
There may be some drawbacks to the above described approaches. For example, decreasing contrast between the indicia and the paper background can interfere with the readability of the document. Also, as copying machines have advanced, even small differences in color intensity may be detected. The use of micro-optical elements may be useful in an anti-copy article, but such elements can be expensive to manufacture.
There is a need for different anti-copy film constructions that can be easily manufactured without the need to minimize the contrast between the paper and the indicia.